This is very true advice. Large upper arms run in my family and let's face it, as a girl, no one wants to have large upper arms! So, when I didn't know anything about working out, I thought that if I worked my arms they would go down in size. How surprised was I when I realized I had this huge muscles - that if I didn't keep working out, would turn into fat? Well, we all know how that story ends... of course they ended up turning into fat and I had to do a whole bunch of sweaty cardio to get rid of my arms, which is what I should have done in the first place.
My point with this entire rant is this = don't be foolish! Take advice like this and do simple, light reps to tone the arms. Otherwise, you're gonna look in the mirror and wonder who the man standing in front of you.
i don't mean to be rude, but there's no such thing as 'toning' a muscle. your muscles can do three things; grow in size, be reduced in size, or maintain size. to achieve the 'ripped' image that most gym rats seek, it is absolutely necessary to obtain a lower body fat. this can be done by integrating a cardio routine, in combination with a well rounded weightlifting sequence. by doing lower weight with higer reps, you are still subjecting your muscles to growth, however the difference between a routine with higher weight and lower reps is the rate of growth. An excess of cardio will certainly hinder muscle growth, which is why most women who don't want to get 'huge' favour a routine heavy on cardio, and lighter on the weights.